MergeSort not working Helppp please :(

I've been working on this mergeSort that has to read from a file then give me the size and then print out the sorted array. However it's giving me the size and printing out the list without sorting it... Helppp please :)

Here's my code:

Code :

---

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.InputMismatchException;
import java.util.NoSuchElementException;
import java.util.Scanner;
 
/**
 *
 * @author fluffy
 */
public class Numbers {
 
    int[] data;
    int size;
 
    Numbers(String fileName) throws IOException {
        data = openFile(fileName);
        data = mergeSort(data);
 
        for (int i = 0; i < data.length; i = i + 1) {
            System.out.println("*" + data[i]);
        }
    }
 
    public int[] openFile(String fileName) throws
            IOException, ArrayIndexOutOfBoundsException,
            InputMismatchException, NoSuchElementException {
 
        int[] a = new int[10];
        int i = 0;
        int k = 0;
        try {
            File inFile = new File(fileName);
            Scanner in = new Scanner(inFile);
 
            //while(in.hasNext()){
            do {
 
                try {
                    k = in.nextInt();
 
                    try {
 
                        a[i] = k;
                    } catch (ArrayIndexOutOfBoundsException e) {
                        System.out.println("Array bound error");
                        a = grow(a);
                        a[i] = k;
                    }
                    i = i + 1;
                } catch (InputMismatchException e) {
                    in.next();
                }
            } while (true);
 
 
        } catch (IOException e) {
            //System.out.println("File 2 not found in openFile3  " + e.getMessage());
        } catch (NoSuchElementException e) {
            size = i - 1;
        }
 
        System.out.println("Size of the array " + size);
 
        return a;
    }
 
    private static int[] grow(int[] a) {
        int[] b = new int[(a.length) * 2];
        for (int i = 0; i <
                a.length; i =
                        i + 1) {
            b[i] = a[i];
        }
 
        return b;
 
    }
 
    public static int[] mergeSort(int[] data) {
        if (data.length > 1) {
 
            int mid = data.length / 2;
 
            int[] first = new int[mid];
            int[] second = new int[data.length - mid];
 
            for (int i = 0; i < first.length; i = i + 1) {
                first[i] = data[i];
            }
            for (int i = 0; i < second.length; i = i + 1) {
                second[i] = data[i + mid];
            }
 
            first = mergeSort(first);
            second = mergeSort(second);
            data = merge(first, second);
 
        }
 
        return data;
    }
 
 
    public static int[] merge(int[] first, int[] second) {
        int i = 0, j = 0;
        int k = 0;
        int[] mergeData = new int[first.length + second.length];
 
        if (i < first.length && j < second.length) {
            if (first[i] < second[j]) {
                mergeData[k] = first[i];
                i = i + 1;
                k = k + 1;
            } else {
                mergeData[k] = second[j];
                j = j + 1;
                k = k + 1;
            }
 
            for (; i < first.length; i = i + 1) {
                mergeData[k] = first[i];
                k = k + 1;
            }
            for (; j < second.length; j = j + 1) {
                mergeData[k] = second[j];
                k = k + 1;
            }
 
 
        }
        return mergeData;
    }
}

---

Your MergeSort method never returns the sorted list.

Code :

---

    public static int[] mergeSort(int[] data) {
        if (data.length > 1) {
 
            int mid = data.length / 2;
 
            int[] first = new int[mid];
            int[] second = new int[data.length - mid];
 
            for (int i = 0; i < first.length; i = i + 1) {
                first[i] = data[i];
            }
            for (int i = 0; i < second.length; i = i + 1) {
                second[i] = data[i + mid];
            }
 
            first = mergeSort(first);
            second = mergeSort(second);
            data = merge(first, second);
            [b]return data;[/b] // need this line
        }

---

it does have the return data; after that } because if i put it where u placed it at the beggining its going to tell me im missing the return statement... i tried it =/

The sorting code is buggy - it does partially sort the list, but not fully.

I suggest you pick a trivial set of values and step through each method by hand keeping track of what happens on paper.

Ahh, didn't look through it that closely ::blush::
dlorde's right, there is a flaw in your merge method. Do what he says and see if you can figure out what it is :)